Knee orthesis appliances are used to stabilise the ligamentous apparatus in the knee.
Where knee orthesis appliances were previously prescribed mainly pre-operatively as a measure to prevent further damage to torn or overstretched ligaments and post-operatively after ligament surgery as protection, nowadays sportsmen from the most varied of disciplines use these knee splints more or less at will to protect against knee or ligament injuries.
The simplest version of the knee orthesis device has a monocentric joint; but it cannot correctly imitate the anatomical movement of the knee joint. The movement or the interplay between all elements of the knee involved in anatomical movement (joint surfaces of the femur and the tibia, cruciate ligaments, patella) is much more complex. This means that knee orthesis appliances having monocentric joints cannot move in synchrony with the thigh and the tibia. The result is annoying frictions, which reduce comfort when wearing one. Since monocentric joints are something of a temporary solution, they are not suitable for sportsmen.
The rolling/sliding movement of the knee joints which actually occurs physiologically and the particular position of the cruciate ligaments was studied and described by Menshik. The result is a so-called "linkover four bar chain" which has been named after him (hereinafter simply referred to as a four bar chain), which imitates the rolling/sliding movement very well and therefore effectively relieves the knee. However this is still far from constructing a knee splint which combines a high level of worn comfort and good management of the ligaments, preconditions which are considered to be self-evident in high performance sport today.